are due to reproductive and sexual behaviour and 3 per cent are due to alcohol. These
behaviours can be predicted by examining individual health beliefs (see Chapters 2, 5,
6 and 9).
2 Stress. Stress has also been shown to have a role to play in cancer. Laudenslager et al.
(1983) reported a study that involved exposing cancer-prone mice to stress (shaking
the cage). They found that if this stressor could be controlled there was a decrease
in the rate of tumour development. However, if the stressor was perceived as
uncontrollable this resulted in an increase in the development. This suggests a role for
stress in the initiation of cancer. However, Sklar and Anisman (1981) argued that an
increase in stress increased the promotion of cancer not its initiation (see Chapter 11
for a discussion of the relationship between stress and illness).
3 Life events. It has also been suggested that life events play a role in cancer (see
Chapter 10 for a discussion of life events). A study by Jacobs and Charles (1980)
examined the differences in life events between families who had a cancer victim and
families who did not. They reported that in families who had a cancer victim there
were higher numbers who had moved house, higher numbers who had changed some
form of their behaviour, higher numbers who had had a change in health status
other than the cancer person, and higher numbers of divorces indicating that life
events may well be a factor contributing to the onset of cancer. However, the results
from a meta-analysis by Petticrew et al. (1999) do not support this suggestion. They
identified 29 studies, from 1966 to 1997, which met their inclusion criteria (adult
women with breast cancer, group of cancer-free controls, measure of stressful life
events) and concluded that although several individual studies report a relationship
between life events and breast cancer, when methodological problems are taken into
account and when the data across the different studies is merged ‘the research shows
no good evidence of a relationship between stressful life events and breast cancer’.Fig. 14-2 The potential role of psychology in cancer340 HEALTH PSYCHOLOGY